Surface water resources in arid regions are increasingly vulnerable to climate variability and growing demand, which calls for accurate, timely, and spatially explicitly monitoring approaches. This study developed a machine learning-based framework for quantifying seasonal and interannual surface water dynamics through multi-sensor fusion approach by combining radar and optical data. Sentinel-1 synthetic aperture radar (SAR), Sentinel-2 multispectral imagery, and Landsat-8 surface reflectance data were processed within the Google Earth Engine (GEE) platform for the period 2015-2021. The study used Random Forest (RF) and Gradient Tree Boosting (GTB) classifier, achieving a remarkable overall classification accuracy from Sentinel-1/2 (OA = 99.34-99.92%; Kappa = 0.8862-0.9983) and Landsat-8 (OA = 99.33-99.76%; Kappa = 0.9859-0.9949). Moreover, positive correlations were observed among water indices, particularly Modified Normalized Difference Water Index (MNDWI) and Normalized Difference Water Index (NDWI), whereas SAR backscatter variables (VV_median and VH_median) indicated a positive correlation with vegetation indices such as Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI). Meanwhile, Shapley Additive Explanations (SHAP) revealed that the MNDWI, NDWI, and SAR backscatter metrics were the most influential predictors of surface water occurrence, followed by vegetation indices and lastly single bands (B2-B8). Seasonal analyses presented greater surface water variability in October and November compared to drier months of May to September. Interannual variability analysis was conducted, indicating maximum surface water extent in 2016 (28,869 km2), and minimum in 2019 (9743 km2). Meanwhile, descriptive analysis with hydroclimatic variables showed that variations in precipitation and evapotranspiration (ET) corresponded with observed spatiotemporal patterns of surface water extent except in 2017. Overall, the proposed framework offers a scalable approach for monitoring surface water variability in data-scarce arid regions, supporting water resource management, drought monitoring, and climate adaptation.
Macroinvertebrates such as snails and crabs influence aspects of salt marsh structure and function through herbivory and bioturbation. However, the effects of physico-chemical variables and habitat composition on their abundance and distribution remain underexplored. This study examined the influence of environmental factors on snail and crab populations across salt marsh habitats in the Berg River Estuary on the west coast of South Africa, hypothesising greater abundance in the intertidal than in the supratidal zone, driven by salinity and elevation. Snail and crab abundance were assessed using manual counts in triplicate quadrats (10 & times; 10 cm for snails; 25 & times; 25 cm for crab burrows) across six transects. Physicochemical variables of sediment and groundwater were also analysed. Six snail species (Davisassiminea sp. 1, Davisassiminea sp. 2, D. capensis, D. globulus, Afrolittorina africana and Melanoides tuberculata) and one crab species (Hymenosoma orbiculare) were recorded. Crab burrow density differed significantly between habitats, with the highest abundance at creek edges (85.37 burrows m-2) and lowest in supratidal habitat (8.57 burrows m-2). Snail richness and abundance declined with elevation; Davisassiminea sp. 2 and D. capensis occurred only at creek edges. Habitat and environmental variables explained 32% of the variation in macroinvertebrate abundance, with sediment conductivity and organic content being key predictors. Generalised linear models indicated that species richness declined with increasing sediment redox potential (t = -2.25, p = 0.025), organic matter (t = -2.07, p = 0.040) and clay content (t = -3.07, p = 0.003). These findings highlight the influence of local environmental conditions in shaping and predicting species distributions under a changing climate.
Generating a cost-effective precious-metal catalyst is essential for achieving low-cost, large-scale green hydrogen production. Since the majority of the overpotential in the proton exchange membrane water electrolyzer arises during the oxygen evolution reaction (OER), the remarkable performance of the IrO2 makes it an ideal anodic catalyst. Herein, a simple, straightforward method was used to prepare an IrO2-loaded transition-metal carbide-supported catalyst. The IrO2 nanoparticles were loaded on TiC (IrxTC1-x) and Ti2AlC (Ir(x)TAC(1-x)) at 20 to 80 wt% IrO2 loadings, using the modified Adams fusion method. A diameter of 2 nm was obtained to exhibit improved OER performance in 0.5 M H2SO4 compared with commercial IrO2. The catalysts showed a uniform distribution of IrO2 nanoparticles on the supports. Overpotentials of 260 and 250 mV were obtained for Ir80TC20 and Ir(80)TAC(20) at 10 mA cm(-2). The prepared Ir80TC20 and Ir(80)TAC(20) showed good OER activity, delivering 10 mA cm(-2) at 1.47 and 1.46 V versus RHE, respectively. The catalysts exhibited OER stability at 10 mA cm(-2) for 73 and 58 h, respectively, for Ir80TC20 and Ir(80)TAC(20). The precursor solution proved significant recyclability, and the study demonstrated a new approach to rapidly design low-cost, high-performance anodic catalysts for overall OER performance.
Abstract This perspective paper examines transition pathways that move small‐scale fisheries from vulnerability towards viability. We understand ‘vulnerability to viability transition pathways’ as integrative and one that extends beyond economic concerns to include social, political, cultural and ecological aspects of small‐scale fisheries. Our findings draw on a reflexive and qualitative assessment of country‐specific case studies from across Africa and Asia to collaboratively identify transition pathways reflected in these contexts. Common pathways that emerged included: (1) building governance networks and partnerships; (2) centring small‐scale fisheries tenure and rights; (3) advancing a gender and intersectional perspective on viability pathways; (4) enhancing opportunities for ecologically sensitive and diversified livelihoods; and (5) co‐creating and co‐producing the knowledge required to catalyse transition pathways. Outcomes of this analysis provide context‐specific foundations upon which to further co‐develop a research agenda on small‐scale fisheries vulnerability to viability transitions. Insights from this analysis also contribute to the identification of the transdisciplinary capacities needed to build more viable and resilient small‐scale fisheries in the context of ongoing debates about blue economy expansion, and in relation to country‐level commitments to implement provisions of the FAO small‐scale fisheries guidelines. In advancing a vulnerability to viability pathways lens, this paper frames small‐scale fisheries transitions as governance‐mediated, justice‐oriented, relational and inherently non‐linear processes. Read the free Plain Language Summary for this article on the Journal blog.
The identification of orogenic unconformities in the high-grade internal zones of orogens requires a multidisciplinary approach. In the northern Scottish Caledonides, isolated occurrences of marble and schist (some kyanite-bearing) do not appear to be integral to the Tonian Loch Ness Supergroup and their affinities are controversial. At Glen Urquhart, structural evidence rules out an allochthonous setting for a kyanite schist-marble succession. Petrological evidence indicates contrasting peak metamorphic conditions between kyanite schist (7-8 kbar and 650 degrees C) and adjacent Tonian paragneiss (9 kbar and 700 degrees C). The U-Pb ages obtained from the youngest detrital zircons within a kyanite schist yield a maximum depositional age of c. 728 Ma, overlapping the c. 725 Ma age of migmatization of the paragneiss. The schist-paragneiss contact is thus interpreted as a tectonically modified unconformity. C-O isotope data from associated marbles and other marble occurrences across the Loch Ness Supergroup suggest correlation with marbles of the late-Cryogenian Easdale Subgroup (Dalradian Supergroup) east of the Great Glen Fault. Deposition of lower parts of the Dalradian Supergroup is likely to have been restricted to east of the fault, but the basin widened so that younger strata progressively onlapped northwestwards and were deposited unconformably on Tonian migmatitic basement.
